1. Field of the Invention
The present invention relates to a substrate processing apparatus and, more particularly, to a method of moving substrates.
2. Prior Art
U.S. Pat. No. 5,512,320 discloses a substrate processing apparatus with a section having a vacuum environment, a section in atmospheric pressure having substrate cassettes and a robot, and load locks or chambers between the two sections. Various substrate transport robot and substrate holding end effectors are also known in the art.
In accordance with one method of the present invention a method of transferring semiconductors substrates from a first location to a second location is provided. The first and second locations are adapted to hold a plurality of the substrates in individual support areas. The method comprises steps of providing a transfer mechanism with a first end effector and a second end effector, the first end effector having a first number of support areas adapted to individually support a first maximum number of substrates thereon and the second end effector having a second number of support areas adapted to individually support a second lower maximum number of substrates thereon; transferring substrates from the first location to the second location with the first end effector; and, when empty individual support areas in the second location are less than the first number of support areas on the first end effector, transferring substrates from the first location to the second location with use of only the second end effector and not the first end effector.
In accordance with another method of the present invention a method of manufacturing a straight transport mechanism for transporting substrates between a first location and a second location is provided comprising steps of determining a number of a maximum substrate holding capacity of the first location; selecting a first end effector and connecting the first end effector to a robot of the substrate transport mechanism, the first end effector having a first substrate area for individually supporting a first maximum number of substrates; and connecting a second end connector to the robot, the second end effector having a second substrate area for individually supporting a second maximum number of substrates which is less than the first maximum number of substrates. The step of selecting the first end effector and the first maximum number of substrates which it can support is based upon a formula.
In accordance with another method of the present invention a method of transferring semiconductor substrates from a first location to a second location is provided. The first and second locations are adapted to hold a plurality of substrates in individual support areas. The method comprises steps of providing a transfer mechanism with a first end effector and a second end effector; transferring substrates from a first substrate cassette at the first location to the second location with at least one of the end effectors; and transferring substrates from a second substrate cassette at the first location to the second location with at least one of the end effectors. The first substrate cassette is unloaded until it is empty and then the second substrate cassette is unloaded until the second location is at a full condition.